In an illumination lamp lighting device, for example, when an LED as a light source of the illumination lamp is brought into open mode destruction because the illumination lamp is disconnected from a power supply circuit, an arc discharge becomes liable to occur. Thus, the necessity of performing a protecting operation is high. Besides, also when the illumination lamp is shorted and can not be used, since there occurs a load abnormality, the protecting operation is preferably performed.
When the load abnormality occurs, the load abnormality is detected and the illumination lamp lighting device can be made to perform the protecting operation. When the load abnormality is detected by monitoring the output voltage of the power supply circuit, in general, a threshold is set, and when the output voltage deviates from the threshold, a determination is made that there is an abnormality.
On the other hand, for example, when the LED is used as the light source of the illumination lamp, a request may be made to enable a specified number of illumination lamps different from each other in lamp voltage within a range of 45 to 95V to be lit by using the same power supply circuit.
However, in related art, since the threshold of the illumination lamp lighting device is fixed, if the illumination lamps are enabled to be lit irrespective of the number thereof, an appropriate protecting operation can not be performed.
An object of an exemplary embodiment is to provide a lighting device and a luminaire, which applies thresholds corresponding to the connected lamp number of illumination lamps and can appropriately control a power supply circuit.